What to Do When Babies Get Mononucleosis

Why infants aren't immune to the "kissing disease"

Mother and baby girl
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Mononucleosis, or mono, may usually be thought of as the "kissing disease" that only teens get, but babies, unfortunately, aren't immune to the condition. 

Learn about the symptoms of mono in infants and small children as well as treatment and diagnosis with this review.

When Mononucleosis Strikes

You can actually get mononucleosis at almost any age. In fact, outside the United States, over 90 percent of children have mono by the time they are five years old.

In the United States, children usually become infected with mono as teens or young adults, when they have classic symptoms, including high fever, sore throat, swollen lymph glands, fatigue, and headache, which may last a week or two.

The older a person who contracts mono is, however, the more severe their symptoms tend to be. An older adolescent with the condition may have symptoms that last for several weeks or months.

Mono May Affect Small Children Differently

Younger children usually have much more mild symptoms of mononucleosis as compared to teens and young adults. So, while a teen might have a high fever and bad sore throat for a week or more, an infant might have no symptoms or mild symptoms.

According to the Centers for Disease Control, these symptoms might be 'indistinguishable from the other mild, brief illnesses of childhood.' So small children with mono may just be a little irritable, with a decreased appetite.

On the other hand, they may have mild upper respiratory infection symptoms, such as a cough, runny nose, or mild fever.

In fact, the symptoms are so mild that no one even suspects that these children might have mono. So how do you know that they had mono then?

Often, it is not until sometime much later when a child is sick with a fever and sore throat (or additional symptoms such as nausea, fatigue or muscle aches) and is thought to have mono that testing is finally done.

This testing, including antibody testing for the Epstein-Barr virus, may then reveal the past infection.

Even if mono is still not suspected, a complete blood count that reveals an atypical lymphocytosis may lead a doctor to suspect the infection is to blame for the child's symptoms. This can also happen when a heterophil antibody test (​monospot) is administered, but this test may come back negative if conducted too soon after your child contracts the illness.

Treatment of Mono in Small Children

When mononucleosis goes undiagnosed in children pediatricians might prescribe them an antibiotic, such as ampicillin, amoxicillin or related penicillin-like antibiotics. These antibiotics won't work, considering that mono is a viral infection. Moreover, children sometimes develop a bad rash as a result of these medications. 

Because antibiotics won't treat mono, physicians often treat mono in patients by advising them to rest. Therefore, parents of infants and small children with the illness should avoid engaging them in strenuous activities. It's also important that parents watch and manage their children's fevers and try to soothe any feelings of discomfort the child has, including a sore throat that typically presents with mono.

 Parents should also make sure that children get enough to drink to prevent dehydration.